MONDAY, May 14 (HealthDay News) -- Feeding tubes increase the risk of bed sores in bedridden dementia patients, according to a new study.

The finding challenges the long-held belief that providing nutrition through feeding tubes helps prevent bed sores or helps promote their healing in this group of patients, the authors of the Brown University-led study said.

The researchers did not look at how feeding tubes could cause bed sores (also called pressure ulcers), but they noted that feeding tubes can cause agitation in patients, who then have to be restrained and sedated. Feeding tubes also may increase the risk of diarrhea.

Together, these factors may cause and worsen bed sores, the researchers said.

The researchers examined data from nursing homes and Medicare claims in order to compare thousands of dementia patients. Among patients who did not initially have a bed sore, 35.6 percent with a feeding tube ended up with at least a stage 2 bed sore, compared with 19.8 percent of patients without a feeding tube.

A stage 2 bed sore is an open sore in the upper layer of the skin. A stage 4 bed sore is the most serious type.

After making statistical adjustments, the researchers concluded that patients with a feeding tube were 2.27 times more likely to develop a bed sore than those without a feeding tube. The risk of developing a stage 4 bed sore was 3.21 times higher for those with a feeding tube.

Among patients who already had a bed sore, short-term improvement in the sore occurred in 27.1 percent of patients with a feeding tube and in 34.6 percent of those without. Patients without a feeding tube were 0.7 times more likely to have an improvement in a sore than those with one, the researchers determined.

The study was published May 14 in the journal Archives of Internal Medicine.

"This study provides new information about the risks of feeding tube insertion in people with advanced [dementia]," lead author Dr. Joan Teno, a gerontologist and professor of health services, policy and practice in the Public Health Program at Brown, said in a university news release.

"We see a substantial risk of people developing a stage 2 and higher [bed sore]," she said. "We believe these risks should be discussed with family members before a decision is made to insert a feeding tube in a hospitalized nursing home resident with advanced [dementia]."